Microwave oscillator and associated circuit



lg- 1939- G. DE VRIES ET AL 2,163,295

MICROWAVE OSCILLATOR AND ASSOCIATED CIRCUIT Filed June 3, 1937 mvs NTORS 5 GERR/T ogre/5s u By C L volv LINDERN ATTORNEY charge tube for usein carrying out our invention.

Patented Aug. 1, 1939 MICROWAVE OSCILLATOR AND ASSOCIATED CIRCUIT Gerritde Vries and Carl G. A. von Lindern, Eindhoven, Netherlands, assignorsto N. V. Philips Floeilampenfabrieken, Eindhoven, Netherands ApplicationJune 3, 1937, Serial No. 146,178 In the Netherlands June 5, 1936 energyfrom the direct current source IS. The tube envelope I! is cemented intoa base 18 in the usual manner. The part a comprises the anodes 2 and 4and the part b the anodes 6, 8, l0 and I2. The cathode of the magnetronis designated by 3. The magnetic field coil I5 is disposed substantiallyin coaxial relation to the linear cathode 3. The anodes 2 and 4 of thepart a are interconnected via an oscillatory circuit 5 to which theoscillations to be multiplied are supplied. The anodes 6, 8, l0 and [2of the part b are divided into two groups in such manner that each anodepertains to a group other than that of the adjacent anodes. Thus, theanodes 6 and i0 pertain to one group and the anodes 8 and I2 to theother group. The anodes 6 and [0 or 8 and I2 respectively of each groupare interconnected electrically through a. conductor F or 9 respectivelyand the middle points of the conductors l and 9 are interconnected via acircuit I l tuned to the doubled frequency of the oscillations occurringin the circuit 5. Y The mid- .dle points of the circuits 5 and II areconnected to the positive pole of the source of voltage which suppliesthe requisite anode voltage and the negative pole of which is connectedto the cathode 3. The source of voltage which supplies the cathodesupply voltage is designated by Hi.

The circuit described operates as follows.

When oscillations are supplied to the circuit 5 an electric alternatingfield is set up the fre quency of which is equal to the frequency of thesaid oscillations between the anodes 2 and 4 and there is in addition amagnetic field. Under the 4 Claims.

This invention relates to a micro-wave oscillator circuit and moreparticularly to a circuit arrangement including a magnetron dischargetube and means for multiplying or dividing the frequency of oscillationsgenerated. Magnetron discharge tubes as commonly built for use inoscillation generators are characterized by a linear cathode co-axiallydisposed with respect to a cylindrical anode system. According to ourinvention the anode system is divided into two groups, arrangedlengthwise of the cathode so that these groups are in effect separatedby a plane normal to the electrode axis. One of these groups preferablycontains a number of segments which is a multiple of the number ofsegments in the other group. The segments of the second group are joinedtogether by a resonant circuit while diametrically opposed segments ofthe first group are joined together by mutually independent resonantcircuits. These resonant circuits are so tuned that fundamentalfrequency oscillations may be generated by virtue of the charges builtup on the anode segments of the group having a lesser number, whileoscillations of a frequency harmonically related to the fundamentalfrequency are developed in the resonant circuits interconnectingdiametrically opposed anode segments of the group having the greaternumber.

It is well known that when a magnetic field is applied to the dischargezone of a magnetron oscillator tube a cloud of electrons is caused torotate about the axis of the cathode. Accordingly, we make use of thisphenomenon in providing a frequency multiplied for use in an ultrahighfrequency system. In order that the invention may be clearly understoodand readily carried into effect it will now be described more fully withreference to the accompanying drawing in which- Figure 1 shows apreferred circuit arrangement including the electrode system of themagnetron discharge tube; and

Fig. 2 illustrates a suitable magnetron disthe cathode is traversed bythe electrons emitted from, the cathode, the electrons emitted from thatpart of the cathode 3 which is inside the part b of the tube beingcarried along by them and describing also a spiral path around thecathode. The speed at which the said path is traversed by the electronsis such that during a half period of the oscillations occurring in. thecircuit 5 the electrons have traversed a path along the circumference ofthe cylindrical surface formed by the anodes which covers an angle of180. While this path is being traversed part of the electrons pass inthe part b of the tube in succession past the anodes 6 and 8 or H! andThe circuit illustrated in Fig. 1 includes a magnetron comprising anumber of anodes which jointly form a cylindrical surface and which aredivided by a surface normal to the axis of the cylindrical shell intotwo systems a and b. The tube itself is shown in Fig. 2, where theelectrode system which is contained in the envelope IT is shown inperspective. Means for exciting I the discharge zone magnetically isillustrated in Fig. 2 as by the magnetic field coil l5 which derives itsperiod of the oscillations supplied to the circuit 5 the circuitconnected between the anodes 6 and 8 on the one hand and the anodes l0and I2 on the other hand is excited once at the anode 8 or H!respectively and once at the anode 8 or l2 reinfluence of these twofields a spiral path around l2 respectively so that during half theoscillations The circuit described is suited both for multiplying andfor dividing high frequency and ultrahigh frequency oscillations. In thelatter case the oscillations the frequency of which is to be divided aresupplied to the circuit 1 I, after which oscillations having a frequencywhich is half the frequency of the oscillations supplied to the circuitH can be derived from the circuit 5. The oscillations the frequency ofwhich is to be multiplied or to be divided may also be generated by themagnetron itself,

The circuit is in addition suited for genera??? a frequency which is thep harmonic of the scillations supplied to the circuit 5 or of theoscillations set up in the circuit 5.

The ratio of the number of anodes of the part a and the number of anodesof the part b governs the harmonic or sub-harmonic that can be obtainedby means of the circuit according to the invention. If the part b of thetube shown in Fig. 1 were to contain six anodes, then the circuitaccording to the invention could be used for tripling the oscillationssupplied to the circuit 5 or set up in this circuit, since in this casethree anodes are traversed during half the oscillation period of theoscillations occurring in the circuit 5 so that the time which elapsesbetween the excitement in phase opposition of the circuit connectedbetween the groups of anodes is a third of half the oscillation periodof the oscillations occurring in the circuit 5.

If in the circuit according to the invention use is made of a magnetronin which the part a of the tube consists of 4 anodes, the part b of 8 or12 anodes, the circuit is also suited for doubling or tripling thefrequency of the oscillations occurring in the circuit 5. In that casethen four anodes of the part a are divided into two groups and theanodes pertaining to one of the groups are connected via an oscillatorycircuit to the anodes of the other group as shown in Fig. 1 for theanodes 6, 8, I0 and I2 of the part b.

The circuit according to the invention may be used particularly whenthere is a need for ultrahigh frequency oscillations having a constantfrequency. Ultra-high frequency oscillations having a frequency of theorder of magnitude of 410 megacycles and higher can no longer begenerated by a retroactively coupled generator and though a magnetrongenerator is suited for the generation of oscillations having such ahigh frequency, the frequency of the oscillations generated by amagnetron generator depends to a marked extent on the voltages suppliedto the electrodes of the magnetron and the frequency of the oscillationsgenerated is consequently variable.

In order to permit of obtaining oscillations having a constant frequencyof the above-mentioned order of magnitude use may be made of a feed-backcoupled generator which is arranged for the generation of a sub-harmonicof the desired frequency, the generated oscillations being supplied to afrequency multiplier according to the invention.

What we claim is:

1. An oscillator in combination with means for producing energyharmonically related to the frequency of the oscillations generated,said oscillator comprising a magnetron discharge tube having a system ofcylindrically formed anode segments and a linear cathode coaxiallydisposed within the anode system, said segments being arranged in twogroups lengthwise of the cathode, the ratio between the numbers ofsegments in said two groups being the same as the ratio between the twofrequencies which are harmonically related, magnetic field excitingmeans for producing a rotating cloud of electrons within the two groupsof anode segments, a resonant circuit interconnecting the anode segmentsof the group having the lesser number of segments, a

resonant circuit interconnecting different pairs of diametricallyopposed anode segments of the further characterized in that the numberof anode segments in one group bears the same ratio to the number ofsegments of the other group as the ratio between the two frequencies towhich the resonant circuits of the two groups are respectively tuned.

4. In a magnetron oscillator and frequency multiplier system of the typewherein the cylindrically formed anode segments are arranged about alinear cathode in two groups, one group being separated from the otherby a plane normal to the electrode axis, and the number of segments inone group being a multiple of the number of segments in the other group,the method of deriving an ultra-high frequency wave which bears aharmonic relation to a fundamental Wave generated by said oscillator,which comprises applying a magnetic field to the discharge Zone,applying operating potentials to the electrodes of one group at suitablevalues for generating the fundamental frequency, resonating the oscilla-4 tory energy charges which are built up on the electrodes of thatgroup, causing a single cloud of electrons to rotate within the entiredischarge zone in unison with the fundamental frequency, and derivingthe harmonically related frequency by resonating the oscillatory energycharges which are built up on the electrodes of the other r up.

GERRIT DE VRIES.

CARL G. A. VON LINDERN.

